Can milk give you straight teeth and a healthy smile?

No. Milk won't make your teeth straight. Its calcium and vitamin d (added) may help strengthen all your bones, including teeth. But it really has no health benefit at all after early childhood. It's all propaganda from the dairy and cattle industry.
Straight teeth, no. But it can help with that healthy smile. Regular visits to your dentist for professional cleanings as well as proper brushing and flossing at home will do wonders.
Calcium. Calcium is necessary for healthy tooth formation. Know that the crowns of all permanent teeth (except wisdom teeth) is usually completed by age 10. Unlike bones, teeth don't renew themselves. Most malocclusions are hereditary. Talk to Dentist.